Which of the following signals specifically indicates that all units should be aware of a potential hazard?

The correct answer is Signal 52, which specifically indicates that all units should be aware of a potential hazard. This signal serves as a warning to ensure that all personnel on duty are informed about situations that may pose risks or require caution in their operations. Being aware of potential hazards is crucial for maintaining safety and preparedness in law enforcement and highway patrol activities.

Other signals, while they may communicate different types of information, do not specifically focus on warning all units about potential hazards. This distinction is vital to ensure that all officers are on the same page regarding situational awareness and can take appropriate precautions in response to the identified risks.